“…[12,13] Diels-Alder, [14] homo-DielsAlder reactions, [15] and Alder-ene reactions, [16] [6 + 2], [17] reductive [3 + 2], [18] and [4 + 2 + 2] cycloadditions, [19] cyclizations of o-iodobenzoates with aldehydes, [20] aryl-sulfur bond formations, [21] Reformatsky reactions, [22] cross-couplings and conjugate additions [23] were also performed under these conditions. Therefore, common catalysts of type CpCoL 2 could be replaced by catalytic systems much easier to handle (and sometimes more efficient [11a] ) to generate benzenes or pyridines by [2 + 2 + 2] approaches.…”